In recent years, there is being developed a display device (e.g., Organic Electroluminescence (EL), etc.) using a light emitting diode that emits light according to the intensity of current supplied. In such a display device, gray scale of a display image is controlled by controlling the amount of current supplied to a light emitting diode using a driving transistor of a pixel. If a characteristic of the driving transistor is varied, the characteristic variation may appear directly on a display image.
Influence of a characteristic variation of the driving transistor on a display image is reduced by using a technique (e.g., referred as a threshold voltage compensation technique) of suppressing a threshold voltage variation of a transistor through a constant current circuit configured to supply a current to the organic electroluminescence constantly. However, such a threshold voltage compensation technique causes an increase in the number of transistors per pixel. Thus, the threshold voltage compensation technique is not practical for high density.